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Oversills/long Sills......


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#1 brownspeed

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Posted 29 November 2020 - 01:30 PM

I ordered up a pair of replacement sills and long sills / oversills have arrived. I'm still going to do a proper job by taking out the originals, but wondered whether to fit these as they are or cut them down to normal length. 

to the untrained idiot (me) if I fit the complete long sill; theres more metal, thus should be more strength added by doing this.

Am I correct in this assumption?. Obviously I'll take pics to prove i've not just done a bodge job over the top. whats the concensus among those more knowledgable than I? 



#2 some1158

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Posted 29 November 2020 - 01:44 PM

Opinion on the structural value of doing this seems to vary. There is also a risk of moisture being trapped in the overlap between the wide sill and the floor. Lots of opinions at https://www.theminif...-to-avoid-them/

 

Personally I would be wary of a Mini with unvented sills even if I was assured that all rust had been cut out before they were installed!



#3 surfblue

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Posted 29 November 2020 - 01:56 PM

I bought my mk1 in 2012, unfortunately when it was restored - bare shell - before I bought it they had used oversills and non original floor pans. Its totally solid though and 8 years on its as good as it was when I bought it. Only done about 4k miles though and its never out in winter. Might be a bigger issue on a daily driver used on gritted winter roads?

#4 sonikk4

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Posted 29 November 2020 - 03:45 PM

Lets put it another way. Did they the factory with them fitted??? the short answer is no and they were only ever supposed to be used as a repair panel.

 

Yes there is a difference in structural strength, they are no thicker than standard mini skin thickness so are not stronger. Plus they form the wrong profile as well.

 

And yes you can chop them down to form a short sill, we did this for my sons car when i ordered them by mistake.

 

And if you are going to do a proper job by removing the old sills, then do a proper job by fitting the correct sills. it will save you a lot of grief and expense further down the road.



#5 sonscar

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Posted 29 November 2020 - 03:53 PM

As Sonikk says not only do they present ideal conditions for rust they do not form the correct section for strength when fitted.After owning a Mini with freshly fitted oversills when I bought it 18 years ago they lasted 15 years as daily driver with patches every 2 or 3 years before I bit the bullet and replaced them.Fitting proper sills was easy.Also when I look at a Mini the first thing I do is look at the sills,could be a stumbling point if you ever decide to sell.Please do it right.Steve..



#6 brownspeed

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Posted 29 November 2020 - 04:36 PM

Thanks folks, thats we we have this forum and that's why I'm in it. I don't profess to know everything (at least when I'm sober!), but theres always somebody who knows better. I've just done the 1st primer coat on them, should save some paint if i chop `em before the second coat!! :proud:



#7 weef

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Posted 29 November 2020 - 10:04 PM

It kind of depends what is left when you take off the original outer panel. It may be the exposed surface is not suitable to get a decent weld, too pitted even after a session with a grinder. The longer section sill gives you the option to reach good metal so a good weld can be achieved. This may not be the desired result that you were hoping for but I think a "long" sill welded to good metal beats a "short" sill attached to a poor surface. If the floor is sound then go for the "short" panel  but this is perhaps not the case here. 

MIG welders are not very forgiving if the surface is not "clean" and forget trying spot welding for the same reason. Oxy/Acc gas gives you the best chance if the surface is doubtful but less people have access to, or can gas weld nowadays. 



#8 brownspeed

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Posted 30 November 2020 - 11:32 AM

yeah! I am spectacularly bad when it comes to gas welding; its more like a firework display! with MIG I'm fairly proficient; even at uphand welding. I also have access to a spot welder which should keep the heat input down on the edge seam welding, thus preserving the doorstep and body paint.



#9 sonscar

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Posted 30 November 2020 - 01:23 PM

Do not get hung up about the inner sill,it is an extension of the floor.A flat sheet of suitable size can be bent to shape and welded in place after cutting out any suspect rust.Do not be tempted to fit oversills overlapping the underside of the floor please.Have welding fun.Steve..






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